| 摘要 |
PURPOSE: A digital television symbol timing synchronous algorithm is provided to square an existing Gardner method with a received signal, and to apply the squared value to a Gardner symbol timing detector, then to recover a symbol clock, thereby restoring symbol timing without frequency components. CONSTITUTION: A Gardner symbol timing recoverer using a prefilter is independently operated from a squared Gardner symbol timing recoverer. The Gardner symbol timing recoverer using the prefilter filters a signal passing through a square root cosine filter1(303) to a prefilter1(304), and uses the filtered signal as an input of a timing detector1(308). The timing detector(308) generates a timing error, amplifies an error value in an amplifier1(312), and obtains an average in a loop filter1(311), then controls parameters of an interpolation filter1(302) in an address calculator1(310). Power of a signal passing through the prefilter1(304) is measured in a power calculator1(306). A distributive calculator1(309) measures changes of the power, and controls a gain value of the amplifier1(312). The distributive calculator1(309) measures how fast a channel changes.
|
